Hi Dan,
I looked into this. For some reason your IP was triggering our security system (
mod_security) and getting blocked. IP's that trigger our system automatically clear after 1 hour. Your IP triggered our system and then auto cleared after one hour and then triggered it again, blocking your IP. This was happening over and over. Our system detected that your IP was trying to inject malware in the url. Basically it appeared as if your browser was trying to inject code and we cant have that. This could be caused by a few things:
1) You have malware on your device. I would recommend scanning your system with a malware scanner:
https://www.malwarebytes.com/ <This is a good free one.
2) Perhaps you had malware in your temporary browser internet files. This is common. The fix is to clear your cache as you did.
3) It could be a false positive (highly unlikely).
Either way you seem to have resolved it on your end by clearing your browser files out. If you experience this again drop me an email at accessnorton at g-m-a-i-l dot com.
Have a great day, cheers
Jerry